I am attempting to develop a method to customize strcpy. I considered two approaches for this implementation. One method involves using memcpy, while the other involves incrementing the pointer and assigning the value.

Implementation using memcpy worked as expected. Code snippet is pasted below.

#include <stdio.h>
#include <string.h>

void mystrcpy(void *dest, void *src, size_t size)
{

    memcpy((char*)dest,(char*)src,size);
    printf("Final - %sn",(char*)dest);
}



int main()
{
    char *src = "ABC";
    char dest[20];
    printf("%p %pn",src,dest);
    mystrcpy(dest,src,sizeof(src));

    return 0;
}

Output is below:

000000000040400C 000000000061FE00
Final - ABC

Hence, I had gone for the second implementation and it is not fully completed. Since I’m just getting started, I saw some behavior that wasn’t what I had anticipated. I am not sure about this. May be I am lagging some very important concepts here.

Here, I consider taking two void* parameters for source and destination. Something similar to below.

void mystrcpy(void *dest, void *src)

Pasting my code below,

#include <stdio.h>
#include <stdint.h>

void mystrcpy(void *dest, void *src)
{

    char *_dest = (char*)dest;
    char *_src = (char*)src;

    *_dest = *_src;
    printf("%c %cn",*_src,*_dest);
    printf("%p %pn",_src,_dest);
    _src++ ; _dest++;


    *_dest = *_src;
    printf("%c %cn",*_src,*_dest);
    printf("%p %pn",_src,_dest);
    _src++ ; _dest++;


    *_dest = *_src;
    printf("%c %cn",*_src,*_dest);
    printf("%p %pn",_src,_dest);
    _src++ ; _dest++;

    *_dest = '';

    printf("Final - %d %d %d  %p %p %pn",_dest[0],_dest[1],_dest[2],&_dest[0],&_dest[1],&_dest[2]);
}



int main()
{
    char *src = "ABC";
    char dest[20];
    printf("%p %pn",src,dest);
    mystrcpy(dest,src);

    return 0;
}

And the output shows

0000000000404034 000000000061FE00

A A

0000000000404034 000000000061FE00

B B

0000000000404035 000000000061FE01

C C

0000000000404036 000000000061FE02

Final – 0 0 0 000000000061FE03 000000000061FE04 000000000061FE05

It was copying the value as expected. I am just confused on the last print,
how it went to xxx03 xxx04 xxx05 instead of xxx00 xxx01 xxx03 !!. And this is the reason why I got garbage value when I printed the _dest.

Please share your thoughts on this.
Thanks in advance.